Manhole openings which are closable by lids are generally used on brewing vessels, such as brewing kettles, whirlpools, lauter tuns, or the like. An operator can enter through the manhole opening into the brewing vessel by opening the lid and can perform maintenance or control work in the vessel. After having completed such work, the operator can leave the brewing vessel through the manhole opening. Before the brewing vessel is put into operation, the lid is again sealingly closed by a locking means. An inspection glass is normally inserted into the lid, so that the interior of the brewing vessel can be inspected without the lid being opened.
In a brewing vessel which is known from German Utility Model G 91 11 870, the locking means of the lid comprises a locking ring which is slidably arranged on the inside of the lid and which is rotatably supported by bolts secured to the inside of the lid and which cooperates with ramps that are arranged on the inside of the frame.
Although such a solution has proved to be successful in practice, it is nevertheless in need of improvement in some respects. To be more specific, the parts of the locking means which are arranged on the inside of the lid form unaccessible spaces or portions, so that deposits may accumulate there during operation of the brewing vessel, the deposits being not easily removable by cleaning. Moreover, the size of an inspection vessel to be mounted in the lid is limited by the locking ring positioned thereunder and the view into the interior of the brewing vessel is impaired by the locking ring.